package com.atwulidun.facade09;

public class Screen {
    // 饿汉式
    private static final Screen instance = new Screen();

    public static Screen getInstance() {
        return instance;
    }

    public static void down() {
        System.out.println("Screen down");
    }

    public static void up() {
        System.out.println("Screen up");
    }

}
